The subject of this invention is a truck for use in conveying/sorting plants.
In such a plant (see FIG. 2), a number of trucks T are provided which are movable along a fixed route R. Each truck T carries a rotating apron A which constitutes a transport platform for objects to be sorted. Each truck is fitted with systems able to position the apron at a number of levels so that the objects can be unloaded into collection devices C disposed along the route and situated at different heights. In order to guarantee the necessary unloading precision, the inlets of these collection devices must be sufficiently large in the horizontal direction, usually at least equal to the length of the trucks.
For this reason, one of the problems which faces the designer of this type of equipment is how to increase the number of outlets in a sorting machine without increasing the length of the plant.
One known solution to this problem involves the use of relatively short unloading hoppers containing devices which further sub-divide the route so as to direct the unloaded objects towards a number of final collectors. This serves to increase the number of outlets without affecting the length of the plant. However, this system is only suitable for equipment designed to handle objects of limited size. If larger objects such as parcels are to be handled, there is a risk of their obstructing the hoppers, thus jamming the machine.
For this reason it has been proposed to provide each collection device with a pair of top and bottom outlets, each directed to a respective final container. The transport platform would be adjusted to a height corresponding to that of the particular outlet into which the objects are to be unloaded.
Commonly owned Patent GB 2,197,633 of the same inventor relates to a truck with a transport platform that can be positioned at different heights by means of a device comprising a pantograph support or an articulated parallelogram, driven by an actuator via a nut and bolt coupling.
These lifting devices pre-position the transport platform at a height corresponding to that of the respective unloading outlet of a collection device, but when they are in the extended (raised) position they are not very rigid, with the result that oscillation is liable to occur because of the horizontal thrusts to which the truck is subjected. Those oscillations can cause, if not an overturning of the load, then at the very least a poor positioning of the load on the transport platform, with the result that the subsequent unloading operation is also imprecise.
The purpose of this invention is to design a truck for conveying/sorting plants, heaving an adjustable-height transport platform which eliminates the annoying oscillation problems mentioned above.
Another purpose of the invention is to design a truck with an adjustable-height transport platform which is reliable in operation and simple and inexpensive to manufacture.